Custom query within hook creates duplicate action

I’m using the object_sync_for_salesforce_push_success hook to run a custom query and then update some user meta after a successful contact/lead sync. This works as intended, but for some reason creates a pending object_sync_for_salesforce_push_record action in the scheduled action that remains indefinitely until it is cancelled manually.

Any idea what would be causing this additional action or how it could be prevented?

Thanks,
Dan

/**
 * SF: Update user meta
 */
function update_user_meta( $op, $response, $synced_object, $object_id, $wordpress_id_field_name ) {
    // do things if the save succeeded
    // $op is what the plugin did - Create, Update, Upsert, Delete
    // $response is what was returned by the $salesforce class. sfapi->response
    // $synced_object is an array like this:
    /*
    $synced_object = array(
        'wordpress_object' => $object,
        'mapping_object' => $mapping_object,
        'queue_item' => false,
        'mapping' => $mapping,
    );
    */
    // $object_id is the salesforce object id
    // $wordpress_id_field_name is the name of the ID field in WordPress

    if($synced_object['mapping']['wordpress_object'] === 'user') {

        $user_id = $synced_object['wordpress_object']['ID'];

        $salesforce = Object_Sync_Salesforce::get_instance();
        $salesforce_api = $salesforce->salesforce['sfapi'];

        if ( is_object( $salesforce_api ) ) {
            $query = "SELECT Contact_s_Account_Type__c, Account.Name, FirstName, LastName FROM Contact WHERE ID = '$object_id'";
            $result = $salesforce_api->query( $query );

            if ( $result['data']['totalSize'] > 0 ) {
                $account_type = $result['data']['records'][0]['Contact_s_Account_Type__c'];
                $account_name = $result['data']['records'][0]['Account']['Name'];
                $first_name = $result['data']['records'][0]['FirstName'];
                $last_name = $result['data']['records'][0]['LastName'];
                if(isset($account_type)) update_user_meta( $user_id, 'user_account_type', $account_type);
                if(isset($account_name)) update_user_meta( $user_id, 'user_company', $account_name);
                if(isset($first_name)) update_user_meta( $user_id, 'first_name', $first_name);
                if(isset($last_name)) update_user_meta( $user_id, 'last_name', $last_name);
                if(isset($first_name) && isset($last_name)) wp_update_user( array( 'ID' => $user_id, 'display_name' => $first_name . ' ' . $last_name) );
            } else {
                update_user_meta( $user_id, 'user_account_type', 'Lead');
            }
        }

    }

}
add_action( 'object_sync_for_salesforce_push_success', __NAMESPACE__ . '\\update_user_meta', 10, 5 );